To find \( f(-1) \) for the function \( f(x) = x^2 + 4x + 8 \), you substitute \(-1\) in place of \(x\):
\[ f(-1) = (-1)^2 + 4(-1) + 8 \]
Calculating each term:
- \((-1)^2 = 1\)
- \(4(-1) = -4\)
- The constant term is \(8\)
Now combine these:
\[ f(-1) = 1 - 4 + 8 \]
Calculating the sums:
\[ 1 - 4 = -3 \] \[ -3 + 8 = 5 \]
Thus,
\[ f(-1) = 5 \]
Therefore, the value of \( f(-1) \) is \( 5 \).